Performance Assessment Tools; Optimizing Performance; Can Your System Deliver The Required Performance - HP DW017B - StorageWorks Ultrium 448 Tape Drive User Manual

Performance Assessment Tools

NOTE:
We strongly recommend that you check the information on our web site at
pat. This contains detailed support information that will enable you to identify bottlenecks and take full
advantage of the performance capabilities of the Ultrium family of tape drives.
You can use our free, standalone performance assessment tools to check tape performance and test
whether your disk subsystem can supply data at the maximum transfer rate.
The tools are located online at http://www.hp.com/support/pat. They are also integrated into HP
Library & Tape Tools, which is available both online (http://www.hp.com/support/tapetools) and
on the CD-ROM supplied with your tape drive.

Optimizing performance

Various factors can affect tape drive performance, particularly in a network environment. In nearly all
cases when performance is not as expected, it is the data rates of the disk subsystem that cause the
bottleneck.
If your tape drive is not performing as well as expected—for example, if backup windows are longer
than expected—please try the tools and consider the following points before contacting HP Support at
http://www.hp.com/support.

Can your system deliver the required performance?

• The Ultrium 1760 tape drive can write uncompressed data at up to 80 MB/s (288 GB/hour) or
compressed data at up to 160 MB/s (576 GB/hour), assuming 2:1 compression.
• The Ultrium 920 tape drive can write uncompressed data at up to 60 MB/s (216 GB/hour) or
compressed data at up to 120 MB/s (432 GB/hour), assuming 2:1 compression.
• The Ultrium 448 tape drive can write uncompressed data at up to 24 MB/s (86 GB/hour) or
compressed data at up to 48 MB/s (172 GB/hour), assuming 2:1 compression.
To obtain this performance it is essential that your whole system can deliver this performance. In most
cases, the backup application will provide details of the average time taken at the end of the backup.
Typical areas where bottlenecks can occur are:
• Disk subsystem
A single spindle disk may not be able to deliver good data throughput at poor compression
ratios. Best practice to ensure good throughput is to utilize multiple disk spindles or data sources.
• System architecture
Be aware of the architecture of your data protection environment.
The aggregation of multiple client sources over a network provides a good way of delivering good
performance, but anything less than Gigabit Ethernet will limit performance for Ultrium tape drives.
Some enterprise class backup applications can be made to interleave data from multiple sources,
such as clients or disks, to keep the tape drive working at optimum performance.
• Tape media type
The data cartridge should match the specification of the tape drive. A lower specification will
have a lower transfer speed (see
• Ultrium 1.6 TB R/W or Ultrium 1.6 TB WORM cartridges with Ultrium 1760 tape drives
• Ultrium 800 GB R/W or Ultrium 800 GB WORM cartridges with Ultrium 920 tape drives
• Ultrium 400 GB R/W cartridges with Ultrium 448 tape drives
• Data and file types
The type of data being backed up or restored can affect performance. Typically, small files incur
greater overhead in processing and access than large files. Equally, data that is not compressible
70
Diagnostic Tools and Performance
"Data cartridges" on page 59). Use:
http://www.hp.com/support/